This invention relates to sump pump apparatus and in particular to an improved sump pump of increased pumping capacity and high reliability.
As explained in my former U.S. Pat. No. 4,177,021, which is incorporated herein by reference, sump pumps of the nature of the present invention are primarily utilized as emergency sump pumps, although features thereof can be utilized in pumps for other purposes. It is important that an emergency sump pump be reliable and, since the emergency sump pump normally functions only under extraordinary conditions, that the sump pump be of an adequate capacity to handle large quantities of water which accumulate in a sump during heavy storms. The pumping rate of the sump pump should be equal to or greater than the rate at which the storm water accumulates in the sump to prevent water overflow and the consequential damage which might thereby be caused.
In prior sump pump apparatus, such as that set forth in referenced U.S. Pat. No. 4,177,021, the pump impeller is situated in close proximity to the pump intake opening at the top of an intake conduit. However, the impeller must be separated a short distance from the intake conduit to avoid frictional engagement of the impeller and intake conduit. Any gap between the conduit and impeller reduces the optimal pumping capacity of the sump pump.
Prior art sump pumps include a switch of some nature to actuate the sump pump when necessary to withdraw storm water from the sump. Such switches may be activated by a float within the sump or may be incorporated into a micro switch which is activated by a particular water pressure within the sump. However, floats tend to become encrusted with contaminants, limiting their reliability, while micro switches can also become encrusted or become jammed by contaminants, such as sand or small stones. In any case, the reliability of the sump pump is compromised if accurate cycling cannot be assured, particularly if the pump is an emergency sump pump.